1. Field of the Invention
The present invention relates to a method of manufacturing a joint body of a ceramic body and a metal body by electrical heating.
2. Description of Related Art
Since ceramics are difficult to form into a complicated shape, they are joined to metal which is easy to machine to obtain a desired component or a part. On the other hand, it is known to use a joint body of ceramic and metal for a heater having a ceramic element which generates heat when applied with a current.
As a method of joining metal and ceramic parts, furnace brazing is widely used. For example, Japanese Unexamined Patent Application Publication (Translation of PCT Application No. 2009-518270) describes an assembly formed by successively attaching a metal piece, an intermediate piece and a ceramic piece by brazing. In this assembly, the intermediate piece serves to change the thermal expansion coefficient stepwise.
However, the brazing material used has a weakness in creep resistivity under high temperature environment. Therefore, joint bodies of ceramic and metal could not be used for purposes assumed to be exposed to high temperature. Vehicle-mounted parts are required to withstand high temperature of over 500° C. to address strengthening of exhaust gas regulation of motor vehicles, which requires increase of exhaust gas temperature. Therefore, joint bodies manufactured using brazing material are not suitable for vehicle-mounted parts. It is possible to join metal and ceramic together directly by heating. However, in this case, there is a concern that cracks may occur in the ceramic.